The present invention relates to a rotating electrical machine, especially to a rotating electrical machine suitable for including a terminal box which contains a support insulator to cool the surrounding of a high voltage bushing which takes out electricity from a stator coil to an outside of the machine and support a power line connected to the high voltage bushing.
In general, a large rotating electrical machine filled with pressurized hydrogen gas in the machine, such as a generator of a thermal power generation, employs a high voltage bushing to take out electricity from a stator coil to the outside of the machine and seal the hydrogen gas in the machine. Some high voltage bushings directly cool an inner conductor with coolant gas. In addition, there are high voltage bushings to allow hydrogen gas to directly flow inside an armature lead of the power line connected to the high voltage bushing for cooling.
The terminal box described above contains an armature lead, a support insulator that supports the armature lead, a flexible lead that connects the armature lead with a lead wire connected to a connection ring for coupling a power supply terminal of the stator coil.
Conventionally, the support insulator described above is installed and fixed horizontally to the terminal box in the vicinity of the flexible lead that connects the armature lead on the high voltage bushing side to the lead wire from the connection line (connection ring) of the stator coil. The support insulator functions as a strength member for supporting the armature lead as well as a cooling flow path for the coolant gas.
For example, JP-S60-183950 (JP-1985-183950) discloses a background art in the present technical field. JP-S60-183950 discloses following features. A lead box (terminal box) of a rotating electrical machine is a cover for protecting a connection portion between an output lead and a power transmission bus bar, and an upper portion of the lead box is attached to a lower portion of an outer casing of the rotating electrical machine and insides of the respective members communicate with each other. The output lead of the rotating electronic machine and the power transmission bus bar are connected through a lead bushing (high voltage bushing) attached to the lower portion of the lead box and a lead connection in the lead box. Since a relatively high voltage is applied to the output lead connection and the lead bushing, there is a need to subject tape winding insulation after a final connection and also ensure an insulation creepage distance and an electrical gap. Furthermore, the respective insides of the rotating electrical machine outer casing and the lead box communicate with each other. To reduce a rise in an ambient temperature due to heat radiation from an energization portion inside the lead box, the coolant gas in the rotating electrical machine outer casing is led to the inside of the lead box to cool the output lead, the lead connection, and the lead bushing.
In the conventional structure described above in which the support insulator is horizontally attached to the terminal box, there is a need to increase a height of the terminal box by the amount corresponding to the attachment of the support insulator. In other words, since there is a need to secure an insulation distance from the high voltage bushing and to secure a work space for maintenance of the high voltage bushing, the height of the terminal box is required to be increased by the amount corresponding to the attachment of the support insulator, causing a disadvantage in terms of strength with the increased height of the terminal box.
In addition, since the inside of the generator (rotating electrical machine) is filled with the pressurized coolant gas, measures that a thickness of a bottom face is increased as size of the terminal box increases and that ribs are attached to a lateral face or a bottom face of the terminal box are required to suppress a deformation of the terminal box.
Unfortunately, JP-S60-183950 discloses nothing about any means for solving the problem described above.